Scale or the like precipitates on the inner surface of a casing or liner in a well, and brushes and even drilling bits are used to remove the scale. However, the scale is not easily removed and small amounts of scale often remain. This is due to the fact that the scale, when precipitating, binds very firmly to the inner surface, so that the scale comes off in layers, leaving a thin layer behind. Also, when performing a cement job where cement is pushed down the casing, a small layer of cement is often left behind, since the pushing plug cannot fully scrape the cement off the casing as it moves down the casing. Since a tubular casing may be slightly oval, the cement pushing plug and the brushes or other known tools are not very good at compensating for the resulting variations in diameter when trying to remove the scale or cement.